In turbomachines, such as aircraft engines and stationary gas turbines, a substantial portion of the losses is caused by a decelerated flow in the gas-carrying flow duct or annulus. Depending on the permissible deceleration values in connection with an ideal annulus, this results in corresponding geometric limitations.
In order to reduce flow losses in the annulus, European Patent Application EP 0 943 784 A1 illustrates an axial turbomachine having multiple stages of airfoils, in which the annulus contour formed by a side wall of the rotor and a side wall of the stator is periodically undulated on the rotor side in the axial direction, and has a depression on the stator side opposite an elevation on the rotor side.
European Patent Application EP 0 799 973 A1 describes a turbomachine having an annulus contour that is provided with a kink angle immediately at the outlet of a rotor blade array. The kink angle is to be dimensioned such that an exit flow from the rotor blade array is homogenized in terms of total pressure and exit flow angle. A downstream stator vane array is provided with a corresponding opposing angle on the inlet side thereof.